SAXS investigation of a cubic to a sponge (L₃) phase transition in self-assembled lipid nanocarriers

Abstract

The encapsulation and release of peptides, proteins, nucleic acids, and drugs in nanostructured lipid carriers depend on the type of the self-assembled liquid-crystalline organization and the structural dimensions of the aqueous and membraneous compartments, which can be tuned by the multicomponent composition of the systems. In this work, small-angle X-ray scattering (SAXS) investigation is performed on the 'melting' transition of the bicontinuous double diamond cubic phase, formed by pure glycerol monooleate (MO), upon progressive inclusion of varying fractions of pharmaceutical-grade glycerol monooleate (GO) in the hydrated system. The self-assembled MO/GO mixtures are found to form diamond (Pn3m) inverted cubic, inverted hexagonal (H(II)), and sponge (L(3)) phases at ambient temperature in excess of aqueous medium without heat treatment. Mixing of the inverted-cubic-phase-forming MO and the sponge-phase-forming GO components, in equivalent proportions (50/50 w/w), yields an inverted hexagonal (H(II)) phase nanostructured carrier. Scattering models are applied for fitting of the experimental SAXS patterns and identification of the structural changes in the aqueous and lipid bilayer subcompartments. The possibility of transforming, at ambient temperature (20 °C), the bicontinuous cubic nanostructures into inverted hexagonal (H(II)) or sponge (L(3)) mesophases may facilitate novel biomedical applications of the investigated liquid crystalline self-assemblies.

Development of pharmaceutical clear gel based on Peceol®, lecithin, ethanol and water: Physicochemical characterization and stability study

“…Lamellar phases L α , reversed hexagonal phases H 2 , cubic phases C and reverse micelles L 2 are the most commonly observed "self-association" phases [6][7][8][9][10][11][12][13].…”

Alkylation of Spiropyran Moiety Provides Reversible Photo-Control over Nanostructured Soft Materials

“…This family of photochromics has been well studied and been shown to induce changes in materials such as liquid crystal phase structure [10], light-induced reversible dissolution of SPmodified block copolypeptide micelles for drug release [8] and modifying the self-assembly of lipid and surfactant membranes [11][12][13][14]. Notably, lipid-based liquid crystal materials are receiving current interest as pulsatile active release systems as they can form thermodynamically stable nanostructures, which control the rate of drug release from the material [15][16][17][18][19][20]. They can also be rendered pH responsive by inclusion of ionizable lipids for selective release during oral drug delivery [21].…”

Characterization and Imaging of Solid Lipid Nanoparticles and Nanostructured Lipid Carriers

“…Packings in the range of 3-5 Å can be characterized by wide-angle X-ray scattering (WAXS) [76,77]. However, layer thickness in the range of 20-50 Å can be characterized by small-angle X-ray scattering (SAXS) [78,79].…”